A key cap provides a protective cover for the bow, or head, of a key. When the bow of a key is inserted into a key cap, the key cap covers the outer surface of the bow and retains the bow (for example, by friction fit), leaving the blade of the key to be exposed outside of the key cap. Keys can be differentiated by fitting their bows with key caps of varying shapes, colours and/or designs. Key caps can also provide improved grip of the covered key and display information for identifying the key.
The shape of a key's bow can be useful in identifying the type of the key. Various different bow shapes for common key types are known. A popular type of key is the “SC1” key, which is compatible with, for example, a Schlage® five-pin, “C” keyway. An SC1 key has a bow that is generally wider than the bows of other common key types, such as “KW1” (Kwikset) and “WR5” (Weiser). As a consequence, a key cap for covering a KW1 key or a WR5 key may not be suitable for use with an SC1 key. For example, the bow of an SC1 key may not fit in a smaller key cap for other common key types. Even if the SC1 bow can be fitted in the smaller key cap, the wider SC1 bow may cause the key cap material to experience an unusual amount of stretching, with the resulting stress eventually causing the key cap to tear. Conversely, a key cap which is appropriately sized to cover an SC1 bow may not provide a secure friction fit for keys that have narrower bows.
U.S. Pat .No. 6,928,845 ('845) discloses a universal key cap that fits around different edged bows of various common house keys. The key cap in '845 includes a hollow chamber for receiving the bow of a key and edged segments molded on an inner surface of the chamber that register with at least one of the edges of the key bow. The edged segments of the key cap are designed to accommodate the varied geometry of the key bows of a plurality of common key types. As a result, the key cap of '845 includes a chamber having a complex internal make-up defined by multiple edges and edged corners. In particular, the chamber of the key cap is designed to be wide enough to house the bow of SC1 keys and, accordingly, the key cap has a large width, which may result in undesirable bulk.
Like reference numerals are used in the drawings to denote like elements and features.